In the majority of chainstitch sewing machines, one or more thread carrying loopers are employed to interloop their thread with the needle thread loop formed beneath the fabric. This action allows the thread to be concatenated into a stitch in the workpiece. In such machines, the looper is usually disposed in an area complicated by other mechanisms; i.e., feed mechanisms, throat plate, thread cutters, loop retainers, and etc. Therefore, operator access to the looper for purposes of servicing is extremely limited.
Mechanisms for retracting the looper to a threading position by bodily moving the looper are known in the art. Examples of this construction are illustrated in U.S. Pat. Nos. 1,912,959; 2,029,233; and, 3,354,851. With the ever increasing speeds of today's machines, however, it is been found necessary to compliment these mechanisms with additional features to prevent undesirable movement of the looper from its operative position while the machine is operating.